The air pumps make a loud noise and lithium ion batteries require care when handling. Roses have sharp prickles, wear gloves to protect from scratches. Hearing protection is recommended. There may be a risk of electric shock in rainy conditions. Wear appropriate protection from the sun: sunscreen and water are recommended.
For this experiment, we will be collecting headspace volatiles with Solid Phase Microextraction (SPME), a method which adsorbs the volatile organic compounds (VOCs) surrounding part of a plant to the SPME fiber. The adsorbed chemicals can then be desorbed with paired Gas Chromatography - Mass Spectrometery (GC-MS) equipment to identify the collected chemistry. SPME extraction is a flexible method which can collect the VOCs from just about anything you can get an container around. For our experiments, we rely on heat-treated oven bags, which are relatively chemically inert after cooking them in an oven at 50°C for a day or so.
The purpose of these experiments is to collect the volatiles emanating from roses under various conditions, including:
By sampling rose VOCs with SPME under these different conditions, we hope to find quantitative and/or qualitative differences in VOC compounds between rose treatments.
Our hypothesis formed from preliminary research where we observed that A. swirskii were preferentially attracted the RRD-infected roses. We think this might be due to differences in the VOCs released from uninfected vs. infected roses. Collecting and comparing chemistry between different roses should allow us to see any qualitative and/or quantitative differences in VOCs released between these groups. This data will give us insight into some of the metabolic changes which may have occurred between different rose groups. Furthermore, our data should indicate which chemicals are worth testing for attractiveness to A. swirskii in olfactometer trials, which can give us insight into which specific VOCs A. swirskii may have been responding to from the RRD-infected roses.
To begin, select a cluster of flowers from a single rose cane, and gently cover it with an oven bag. Seal the end of the oven bag over the base of the rose cane with a zip tie so that the air is trapped around the